Azure Logic Apps (Consumption): HTTP Action to POST multipart/form-data with Files and Fields

In this post, let's see how we can POST multipart/form-data with files and fields using a HTTP action in a Consumption Azure Logic App.

I have the following Test API which I am going to call from the Logic App.

WebApplicationBuilder builder = WebApplication.CreateBuilder(args);
 
WebApplication app = builder.Build();
 
app.UseHttpsRedirection();
 
app.MapPost("/api/Files", async (IFormCollection formCollection) =>
{
    IFormFile? file = formCollection.Files.SingleOrDefault();
 
    if (file == null || file.Length == 0)
    {
        return Results.BadRequest("No file uploaded.");
    }
 
    string fileName = file.FileName;
 
    // Save file and ensure file is good
    string filePath = Path.Combine(@"<some-location>", fileName);
    using FileStream stream = File.Create(filePath);
    await file.CopyToAsync(stream);
 
    return Results.Ok(new
    {
        fileName,
        fileSize = file.Length,
        someField = formCollection["someField"].ToString()
    });
})
.DisableAntiforgery();
 
app.Run();

In my Logic App, I have a variable called file  of type object and it's populated with data. 

{
  "fileName": "<OMITTED>", // some-file.pdf
  "base64Content": "<OMITTED>", // Base 64 encoded content
  "contentType": "<OMITTED>" // application/pdf
}

And now let's add the HTTP action as follows:

HTTP Action

Code for Body is below.

{
  "$content-type": "multipart/form-data",
  "$multipart": [
    {
      "headers": {
        "Content-Disposition": "form-data; name=\"file\"; filename=\"@{variables('file')?['fileName']}\""
      },
      "body": {
        "$content": "@{variables('file')?['base64Content']}",
        "$content-type": "@{variables('file')?['contentType']}"
      }
    },
    {
      "headers": {
        "Content-Disposition": "form-data; name=\"someField\""
      },
      "body": "Hello World!"
    }
  ]
}

And now when the HTTP action is executed, I can see the values are getting passed correctly.

API Endpoint

Hope this helps.

Happy Coding.

Regards,

Jaliya